Hypnosis is becoming a more common practice now that it is being used in major hospitals such as MD Anderson a cancer research hospital based in Houston.
Hypnosis itself is works through the power of suggestion. The brain receives signals suggesting something is so and the body cannot determine if it is real or not and thus follows those suggestions.
In medical science, they call such things a placebo affect. Meaning a substance or
affirmation is recognize by the body as though it really happened and thus follows this through physical behavior or change. This is how its possible to suggest someone to stop smoking or to lose weight. The actions to follow through become easier and more congruent when the mind and body are in sync.